Traditional methods of manufacturing antiperspirant and/or deodorant sticks utilize hot processes that form a melt, or near molten fluid, which is poured or forced into a container and then cooled to form a solid stick.
In the underarm area, art of interest includes U.S. Patent Application No. 2001/0041169 A1 to Allan et al for Unilever, published Nov. 15, 2001, which describes a filling process for containers wherein the product is close to the setting temperature. The process uses a screw extruder (particularly a twin screw) to fill packages.
U.S. Pat. No. 6,261,579 to Roulier et al for L'Oreal describes the use of compression and extrusion in a twin screw extruder for the formation of a cosmetic hydrating gel. The gel is composed of 20% or more water soluble or hydrophilic gelling agents in the presence of water.
U.S. Pat. No. 6,045,814 to Roulier et al for L'Oreal describes rigid gels containing at least 20% of one or more hydrophilic gelling agents. The gels are obtained in the presence of water by mixing, blending, compression and extrusion in a twin-screw extruder. This reference includes pigment in the composition later removed in U.S. Pat. No. 6,261,579.
U.S. Pat. No. 5,490,979 to Kasat et al for Colgate Palmolive describes composition and method of manufacture of a clear stick antiperspirant. This reference describes a method which uses a twin screw extruder to create separate mixing chambers where temperatures can be controlled and prevent degradation of heat sensitive ingredients.
PCT Application 99/07429 to Allan et al for Hindustan Lever Ltd. describes a compartmented progressive pitched screw which acts as mixer/delivery/temperature controller, and delivers a uniform product to be filled into standard AP containers at temperatures between 0 and 3 degrees below the melt point of the composition. Benefits are uniformity of active content obtained by eliminating sedimentation, and an ability to add temperature sensitive ingredients late in the process.
U.S. Pat. No. 4,688,609 to Diaz for Fluid Packaging Co. describes a system for injecting molten product into deodorant stick containers with automatically dispensing metered amounts of viscous product in assembly line fashion into a series of containers.
PCT Application 01/02824 to Allan et al for Hindustan Lever Ltd. describes the application of the filling apparatus in PCT 99/07429, to the production and filling of soft solid product formulations via batch or continuous means, with screw extrusion filling under pressure.
U.S. Pat. No. 4,678,420 to Inoue for Inoue-Japax Research describes an injection molding method for plastic melts and formation of finished units using a feed screw and piston, under pressure and with temperature control.
U.S. Pat. No. 6,338,840 to Allan, et al for Unilever describes a process and apparatus for the production of an antiperspirant and/or deodorant product by a continuous process involving injection molding.
Specific patents that disclose extrusion as a method of producing stick deodorants and antiperspirants include the following: U.S. Pat. Nos. 6,161,579 and 6,045,814 to Roulier, et al. disclose water-soluble gels which are kept at elevated temperature through the extrusion process in the 60–100° C. range. PCT Application WO 00/19861 to Allan et al. for Lever (see also WO 00/41169 A1) discloses a process using temperatures between 0–3° C. below the melt point of the composition while filling containers. The apparatus described is best described as a screw feeder with temperature control rather than an extruder that compresses the composition. U.S. Pat. No. 5,316,712 to Ono et al, discloses an extrusion/injection molding of an oil and powder mixture into a mold to form a cosmetic. U.S. Pat. No. 4,688,609 to Diaz discloses a device for filling sticks using a piston and air actuated plunger to control flow and fill weight of molten material. U.S. Pat. No. 4,897,236 to Rabiger et al, discloses a process and apparatus that can be used for extruding rubber.
In other non-antiperspirant/deodorant fields, references of interest include U.S. Pat. No. 5,316,712 to Ono et al for JO Cosmetics which describes an injection molding method for making cosmetics using a piston to force a molten composition into a die and cooling it there, then discharging the product from the die for packaging; and U.S. Pat. No. 4,897,236 to Rabiger et al for Herman Berstorff Maschinenbau which describes a method and apparatus for the continuous manufacture of rubber or polymer based mixtures containing additives. The ingredients for the mixture are fed into a twin screw extruder and masticated and homogenized therein. Recycling is described.
These previous attempts are not completely satisfactory in accomplishing the objects of the present invention since they require elevated temperatures and a prescribed package form in which to deposit the product while it is hot. Thus, the objects of the invention include having the ability to extrude the stick formula ingredients at temperatures well below the melting point of the formula, and being able to create solid sticks without requiring a package form to shape the product. Further advantages of the invention include (1) greater flexibility in packaging the final product; (2) increased uniformity in product since solid products are less likely to have the individual ingredients settle out during the process; (3) reduction or elimination of voids and cavities, shrinkage and cracking since relatively little cooling takes place; (4) increased ability to use volatile products that would otherwise be lost because of heat; and (5) greater ability to use temperature sensitive materials that might otherwise degrade because of exposure to elevated temperatures (for example, fragrances). Yet another advantage of the invention is (6) the ability to make antiperspirants and/or deodorants which have colored striations, or other aesthetics not possible in other conventional manufacturing routes for molten sticks.